J. Hydrol. Hydromech., Vol. 69, No. 4, 2021, p. 357 - 359, doi: 10.2478/johh-2021-0031
Information, English

Giora J. Kidron, Maik Veste, Ľubomír Lichner: Biological factors impacting hydrological processes: Pecularities of plants and biological soil crusts

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• Data not available
  
  KEY WORDS: Data not available
  
  Address:
  - Giora J. Kidron, Institute of Earth Sciences, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel. (Corresponding author. Tel.: Fax.: Email: kidron@mail.huji.ac.il)
  - Maik Veste, Institute of Environmental Sciences, Soil Protection and Recultivation, Brandenburg University of Technology Cottbus-Senftenberg, Konrad-Wachsmann-Allee 6, 03046 Cottbus, Germany.
  - Ľubomír Lichner, Institute of Hydrology, Slovak Academy of Sciences, Dúbravská cesta 9, 84104 Bratislava, Slovakia.

J. Hydrol. Hydromech., Vol. 69, No. 4, 2021, p. 360 - 368, doi: 10.2478/johh-2021-0028
Review, English

Giora J. Kidron: The role of biocrust-induced exopolymeric matrix in runoff generation in arid and semiarid zones – a mini review

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• Although playing an important role in shaping the environment, the mechanisms responsible for runoff initiation and yield in arid and semiarid regions are not yet fully explored. With infiltration-excess overland flow, known also as Hortonian overland flow (HOF) taking place in these areas, the uppermost surface 'skin' plays a cardinal role in runoff initiation and yield. Over large areas, this skin is composed of biocrusts, a variety of autotrophs (principally cyanobacteria, green algae, lichens, mosses) accompanied by heterotrophs (such as fungi, bacteria, archaea), which may largely dictate the infiltration capability of the surface. With most biocrust organisms being capable of excreting extracellular polymeric substances (EPS or exopolymers), and growing evidence pointing to the capability of certain EPS to partially seal the surface, EPS may play a cardinal role in hindering infiltration and triggering HOF. Yet, despite this logic thread, great controversy still exists regarding the main mechanisms responsible for runoff generation (runoff initiation and yield). Elucidation of the possible role played by EPS in runoff generation is the focus of the current review.
  
  KEY WORDS: Biological soil crusts; Extracellular polymeric substances; Pore clogging; Hydrophobicity; Infiltration-excess overland flow; Water repellency.
  
  Address:
  - Giora J. Kidron, Institute of Earth Sciences, The Hebrew University of Jerusalem, Givat Ram Campus, Jerusalem 91904, Israel. (Corresponding author. Tel.:+972-54-4967-271 Fax.: 972-2-566-2581 Email: kidron@mail.huji.ac.il)

J. Hydrol. Hydromech., Vol. 69, No. 4, 2021, p. 369 - 377, doi: 10.2478/johh-2021-0022
Scientific Paper, English

Sylvie Laureen Drahorad, Vincent J. M. N. L. Felde, Ruth H. Ellerbrock, Anja Henss: Water repellency decreases with increasing carbonate content and pH for different biocrust types on sand dunes

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• Biocrusts are biological communities that occupy the soil surface, accumulate organic matter and mineral particles and hence strongly affect the properties of the soils they cover. Moreover, by affecting water repellency, biocrusts may cause a preferential infiltration of rainwater, with a high impact on the formation of local water pathways, especially for sand dunes. The aim of this study is to shed light on the connections between water repellency and pH, carbonate and organic matter content in two dune ecosystems with different biocrust types. For this, we used contact angle measurements, gas volumetric carbonate determination and organic matter characterization via FT-IR and TOFSIMS. In both ecosystems, moss-dominated biocrusts showed higher water repellency and higher amounts of organic matter compared to algal or cyanobacterial biocrusts. Surprisingly, the biocrusts of the two dune systems did not show differences in organic matter composition or organic coatings of the mineral grains. Biocrusts on the more acidic dunes showed a significantly higher level of water repellency as compared to higher carbonate containing dunes. We conclude that the driving factor for the increase in water repellency between cyanobacterial and moss-dominated biocrusts within one study site is the content of organic matter. However, when comparing the different study sites, we found that higher amounts of carbonate reduced biocrust water repellency.
  
  KEY WORDS: Organic matter composition; Surface characteristics; TOF-SIMS; Biocrust; Carbonate content; Water repellency.
  
  Address:
  - Sylvie Laureen Drahorad, Institute for Soil Science and Soil Conservation, Research Centre for BioSystems, Land Use and Nutrition (iFZ), Justus Liebig University Giessen, Giessen, Germany. Institute for Physical Chemistry, Justus Liebig University Giessen, Giessen, Germany. (Corresponding author. Tel.:+49(0)641-9934522 Fax.: Email: Sylvie.Drahorad@phys.chemie.uni-giessen.de)
  - Vincent J. M. N. L. Felde, Department of Soil Science, University of Kassel, Witzenhausen, Germany. Institute of Soil Science, Leibniz University Hanover, Hanover, Germany.
  - Ruth H. Ellerbrock, Working Group: Hydropedology, Research Area 1 "Landscape Functioning", Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany.
  - Anja Henss, Institute for Physical Chemistry, Justus Liebig University Giessen, Giessen, Germany.

J. Hydrol. Hydromech., Vol. 69, No. 4, 2021, p. 378 - 386, doi: 10.2478/johh-2021-0026
Scientific Paper, English

Hongjie Guan, Xinyu Liu: Biocrust effects on soil infiltrability in the Mu Us Desert: Soil hydraulic properties analysis and modeling

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• The presence of biocrusts changes water infiltration in the Mu Us Desert. Knowledge of the hydraulic properties of biocrusts and parameterization of soil hydraulic properties are important to improve simulation of infiltration and soil water dynamics in vegetation-soil-water models. In this study, four treatments, including bare land with sporadic cyanobacterial biocrusts (BL), lichen-dominated biocrusts (LB), early-successional moss biocrusts (EMB), and latesuccessional moss biocrusts (LMB), were established to evaluate the effects of biocrust development on soil water infiltration in the Mu Us Desert, northwest of China. Moreover, a combined Wooding inverse approach was used for the estimation of soil hydraulic parameters. The results showed that infiltration rate followed the pattern BL > LB > EMB > LMB. Moreover, the LB, EMB, and LMB treatments had significantly lower infiltration rates than the BL treatment. The saturated soil moisture (θs) and shape parameter (αVG) for the EMB and LMB treatments were higher than that for the BL and LB treatments, although the difference among four treatments was insignificant. Water retention increased with biocrust development at high-pressure heads, whereas the opposite was observed at low-pressure heads. The development of biocrusts influences van Genuchten parameters, subsequently affects the water retention curve, and thereby alters available water in the biocrust layer. The findings regarding the parameterization of soil hydraulic properties have important implications for the simulation of eco-hydrological processes in dryland ecosystems.
  
  KEY WORDS: Cyanobacteria; Lichen; Moss; Infiltration; Inverse approach; Hydraulic parameter.
  
  Address:
  - Hongjie Guan, Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China. Key Laboratory of State Forestry Administration on Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China. Beijing Engineering Research Center of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China. (Corresponding author. Tel.: Fax.: Email: guanhong311@163.com)
  - Xinyu Liu, State Key Laboratory of Earth Surface Processes and Resource Ecology, MOE Engineering Research Center of Desertification and Blown-sand Control, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China.

J. Hydrol. Hydromech., Vol. 69, No. 4, 2021, p. 387 - 399, doi: 10.2478/johh-2021-0029
Scientific Paper, English

Roberto Lázaro, Adolfo Calvo-Cases, Eva Arnau-Rosalén, Consuelo Rubio, David Fuentes, Clément López-Canfín: Defining minimum runoff length allows for discriminating biocrusts and rainfall events

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• The runoff coefficient (RC) is widely used despite requiring to know the effective contributing area, which cannot be known a priori. In a previous work, we defined runoff length (RL), which is difficult to measure. This work aimed to define the minimum RL (mRL), a quantitative and easy proxy of RL, for use in a pilot study on biocrusts in the Tabernas Desert, Spain. We show that RC decreases according to a hyperbola when the contributing area increases, the independent variable being the length of the effective contributing area and its coefficient involving the effects of rainfall and surface features and antecedent conditions. We defined the mRL as the length of the effective contributing area making RC = 1, which is calculated regardless of the area. We studied mRL from three biocrust types and 1411 events clustered in seven categories. The mRL increased with rain volume and intensity, catchment area and slope, whereas plant cover and biocrust succession (with one exception) had a negative effect. Depending on the plot, mRL reached up 3.3–4.0 m on cyanobacterial biocrust, 2.2–7.5 m on the most widespread lichens, and 1.0–1.5 m on late-successional lichens. We discuss the relationships of mRL with other runoff-related parameters.
  
  KEY WORDS: Semiarid; Biological soil crust; Runoff connectivity; Length slope factor; Infiltration; Tabernas Desert.
  
  Address:
  - Roberto Lázaro, Estación Experimental de Zonas Áridas (CSIC), Carretera Sacramento s/n, 04120 La Canada, Almería, Spain. (Corresponding author. Tel.: Fax.: Email: lazaro@eeza.csic.es)
  - Adolfo Calvo-Cases, Inter-University Institute for Local Development (IIDL), Department of Geography, University of Valencia, Edifici d'Instituts, 4a Planta C/ Serpis 29, 46022, Valencia, Spain.
  - Eva Arnau-Rosalén, Department of Natural Sciences, Manchester Metropolitan University, John Dalton Building E410a, Chester Street, Manchester M1 5GD, UK.
  - Consuelo Rubio, Estación Experimental de Zonas Áridas (CSIC), Carretera Sacramento s/n, 04120 La Canada, Almería, Spain.
  - David Fuentes, Department of Ecology, University of Alicante, C/ de San Vicente del Raspeig, s/n, 03690 San Vicente del Raspeig, Alicante, Spain. Ecodrone Works, C/ Senores Maripino Rosello, 4, 03550, Sant Joan d’Alacant, Spain.
  - Clément López-Canfín, Estación Experimental de Zonas Áridas (CSIC), Carretera Sacramento s/n, 04120 La Canada, Almería, Spain. Departamento de Física Aplicada, Universidad de Granada, Avenida Fuente Nueva s/n, 18071 Granada, Spain.

J. Hydrol. Hydromech., Vol. 69, No. 4, 2021, p. 400 - 420, doi: 10.2478/johh-2021-0030
Scientific Paper, English

Marc Muselli, Daniel Beysens: Mapping past, present and future dew and rain water resources for biocrust evolution in southern Africa

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• Biocrust sustainability relies on dew and rain availability. A study of dew and rain resources in amplitude and frequency and their evolution is presented from year 2001 to 2020 in southern Africa (Namibia, Botswana, South Africa) where many biocrust sites have been identified. The evaluation of dew is made from a classical energy balance model using meteorological data collected in 18 stations, where are also collected rain data. One observes a strong correlation between the frequency of dew and rain and the corresponding amplitudes. There is a general tendency to see a decrease in dew yield and dew frequency with increasing distance from the oceans, located west, east and south, due to decreasing RH, with a relative minimum in the desert of Kalahari (Namibia). Rain amplitude and frequency decreases when going to west and north. Short-term dew/rain correlation shows that largest dew yields clearly occur during about three days after rainfall, particularly in the sites where humidity is less. The evolution in the period corresponds to a decrease of rain precipitations and frequency, chiefly after 2010, an effect which has been cyclic since now. The effect is more noticeable towards north. An increase of dew yield and frequency is observed, mainly in north and south-east. It results in an increase of the dew contribution with respect to rain, especially after 2010. As no drastic changes in the distribution of biomass of biocrusts have been reported in this period, it is likely that dew should compensate for the decrease in rain precipitation. Since the growth of biocrust is related to dew and rain amplitude and frequency, future evolution should be characterized by either the rain cycle or, due to global change, an acceleration of the present tendency, with more dew and less rainfalls.
  
  KEY WORDS: Biocrust; Dew and rain evolution; Dew/rain ratio; Dew/rain correlation; Southern Africa; Climate change.
  
  Address:
  - Marc Muselli, Universita di Corsica Pasquale Paoli, Avenue du 9 septembre, BP 52, 20250 Corte, France. OPUR, 2 rue Verderet, 75016 Paris, France.
  - Daniel Beysens, OPUR, 2 rue Verderet, 75016 Paris, France. Physique et Mécanique des Milieux Hétérogenes, CNRS, ESPCI Paris - PSL University, Sorbonne Université, Sorbonne Paris Cité, 10 rue Vauquelin, 75005 Paris, France. (Corresponding author. Tel.:+33(0)689864717 Fax.: Email: daniel.beysens@espci.fr)

J. Hydrol. Hydromech., Vol. 69, No. 4, 2021, p. 421 - 435, doi: 10.2478/johh-2021-0021
Scientific Paper, English

Sonja M. Thielen, Corinna Gall, Martin Ebner, Martin Nebel, Thomas Scholten, Steffen Seitz: Water’s path from moss to soil: A multi-methodological study on water absorption and evaporation of soil-moss combinations

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• Mosses are often overlooked; however, they are important for soil-atmosphere interfaces with regard to water exchange. This study investigated the influence of moss structural traits on maximum water storage capacities (WSCmax) and evaporation rates, and species-specific effects on water absorption and evaporation patterns in moss layers, mosssoil- interfaces and soil substrates using biocrust wetness probes. Five moss species typical for Central European temperate forests were selected: field-collected Brachythecium rutabulum, Eurhynchium striatum, Oxyrrhynchium hians and Plagiomnium undulatum; and laboratory-cultivated Amblystegium serpens and Oxyrrhynchium hians. WSCmax ranged from 14.10 g g–1 for Amblystegium serpens (Lab) to 7.31 g g–1 for Plagiomnium undulatum when immersed in water, and 11.04 g g–1 for Oxyrrhynchium hians (Lab) to 7.90 g g–1 for Oxyrrhynchium hians when sprayed, due to different morphologies depending on the growing location. Structural traits such as high leaf frequencies and small leaf areas increased WSCmax. In terms of evaporation, leaf frequency displayed a positive correlation with evaporation, while leaf area index showed a negative correlation. Moisture alterations during watering and desiccation were largely controlled by species/substrate-specific patterns. Generally, moss cover prevented desiccation of soil surfaces and was not a barrier to infiltration. To understand water’s path from moss to soil, this study made a first contribution.
  
  KEY WORDS: Biological soil crusts; Bryophytes; Ecohydrology; Moss structure; Moss hydrology; Rainfall interception.
  
  Address:
  - Sonja M. Thielen, Invertebrate Palaeontology and Palaeoclimatology, Department of Geosciences, University of Tübingen, Schnarrenbergstr. 94-96, 72076 Tübingen, Germany.
  - Corinna Gall, Soil Science and Geomorphology, Department of Geosciences, University of Tübingen, Rümelinstr. 19-23, 72070 Tübingen, Germany.
  - Martin Ebner, Biogeology, Department of Geosciences, University of Tübingen, Hölderlinstr. 12, 72074 Tübingen, Germany.
  - Martin Nebel, Nees-Institute for Biodiversity of Plants, University of Bonn, Meckenheimer Allee 170, 53115 Bonn, Germany.
  - Thomas Scholten, Soil Science and Geomorphology, Department of Geosciences, University of Tübingen, Rümelinstr. 19-23, 72070 Tübingen, Germany.
  - Steffen Seitz, Soil Science and Geomorphology, Department of Geosciences, University of Tübingen, Rümelinstr. 19-23, 72070 Tübingen, Germany. (Corresponding author. Tel.:+49 (0)7071-29-77523 Fax.: Email: steffen.seitz@uni-tuebingen.de)

J. Hydrol. Hydromech., Vol. 69, No. 4, 2021, p. 436 - 446, doi: 10.2478/johh-2021-0025
Scientific Paper, English

Martin Jančo, Pavel Mezei, Andrej Kvas, Michal Danko, Patrik Sleziak, Jozef Minďáš, Jaroslav Škvarenina: Effect of mature spruce forest on canopy interception in subalpine conditions during three growing seasons

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• The interception process in subalpine Norway spruce stands plays an important role in the distribution of throughfall. The natural mountain spruce forest where our measurements of throughfall and gross precipitation were carried out, is located on the tree line at an elevation of 1,420 m a.s.l. in the Western Tatra Mountains (Slovakia, Central Europe). This paper presents an evaluation of the interception process in a natural mature spruce stand during the growing season from May to October in 2018–2020. We also analyzed the daily precipitation events within each growing season and assigned to them individual synoptic types. The amount and distribution of precipitation during the growing season plays an important role in the precipitation-interception process, which confirming the evaluation of individual synoptic situations. During the monitored growing seasons, precipitation was normal (2018), sub-normal (2019) and above-normal (2020) in comparison with long-term precipitation (1988–2017). We recorded the highest precipitation in the normal and above-normal precipitation years during the north-eastern cyclonic synoptic situation (NEc). During these two periods, interception showed the lowest values in the dripping zone at the crown periphery, while in the precipitation sub-normal period (2019), the lowest interception was reached by the canopy gap. In the central crown zone near the stem, interception reached the highest value in each growing season. In the evaluated vegetation periods, interception reached values in the range of 19.6–24.1% of gross precipitation total in the canopy gap, 8.3–22.2% in the dripping zone at the crown periphery and 45.7–51.6% in the central crown zone near the stem. These regimes are expected to change in the Western Tatra Mts., as they have been affected by windstorms and insect outbreaks in recent decades. Under disturbance regimes, changes in interception as well as vegetation, at least for some period of time, are unavoidable.
  
  KEY WORDS: Precipitation; Interception; Synoptic types; Norway spruce (Picea abies L. Karst.); Growing season.
  
  Address:
  - Martin Jančo, Institute of Hydrology, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia.
  - Pavel Mezei, Institute of Forest Ecology, Slovak Academy of Sciences, Štúrova 2, 960 53 Zvolen, Slovakia. Department of Forest Protection, Faculty of Forestry, Technical University in Zvolen, T.G. Masaryka 24, 960 01 Zvolen, Slovakia.
  - Andrej Kvas, Department of Natural Environment, Faculty of Forestry, Technical University in Zvolen, T.G. Masaryka 24, 960 01 Zvolen, Slovakia.
  - Michal Danko, Institute of Hydrology, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia.
  - Patrik Sleziak, Institute of Hydrology, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia.
  - Jozef Minďáš, Ecological & Forestry Research Agency EFRA, Medený hámor 11, 974 01 Banská Bystrica, Slovakia.
  - Jaroslav Škvarenina, Department of Natural Environment, Faculty of Forestry, Technical University in Zvolen, T.G. Masaryka 24, 960 01 Zvolen, Slovakia. (Corresponding author. Tel.:+421 455 206 209 Fax.: Email: skvarenina@tuzvo.sk)

J. Hydrol. Hydromech., Vol. 69, No. 4, 2021, p. 447 - 455, doi: 10.2478/johh-2021-0027
Scientific Paper, English

D.A.L. Leelamanie, H.I.G.S. Piyaruwan, P.K.S.C. Jayasinghe, P.A.N.R. Senevirathne: Hydrophysical characteristics in water-repellent tropical Eucalyptus, Pine, and Casuarina plantation forest soils

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• Soil water repellency (SWR) reduces the rates of wetting in dry soils and is known to interfere with water movement into as well as within the soils. The objective of this study was to investigate the hydrophysical characteristics of three water-repellent tropical exotic plantation forest soils in wet and dry seasons. The study sites were Eucalyptus grandis (EG), Pinus caribaea (PC), and Casuarina equisetifolia (CE) plantation forest soils located in the up-country intermediate zone (EG and PC), and low-country dry zone (CE). Field experiments were conducted to measure the infiltration rate, unsaturated hydraulic conductivity (k), water sorptivity (SW). Laboratory experiments were conducted to measure the potential SWR and water entry value (hwe). All three soils showed higher SWR in the dry season, where CE soils showed the highest. The EG soils showed the highest SWR in the wet season. Although SWR in all soils decreased with increasing depth in the wet season, only CE soils showed a significant decrease in SWR with soil depth in the dry season. Compared with the wet season, the k (–1 cm) was lower and hwe was higher in the dry season. However, SW did not show a significant difference between wet and dry seasons. Initial infiltration rate and k (–1 cm) showed a negative correlation with contact angle in all three soils. Soils showed positive linear correlations between k (–1 cm) and SW, and negative linear correlations between SW and hwe showing that surface water absorption is related to both subsurface unsaturated water flow and surface water entry pressure. It was clear that the water entry into soils and the subsurface water flow were hindered by the SWR. High water entry values in the dry season predict high potentials for intensified surface runoff and topsoil erosion. Future research will be required on the interactions between soil biology and soil properties such as pore structure that would influence water flow into and within soils.
  
  KEY WORDS: Eucalyptus grandis; Pinus caribaea; Casuarina equisetifolia; Hydrophysical characteristics; Water repellency.
  
  Address:
  - D.A.L. Leelamanie, Department of Soil Science, Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya 81100, Sri Lanka. (Corresponding author. Tel.:+94-71-861-4380 Fax.: +94-41-2292384 Email: leelamanie@soil.ruh.ac.lk; leelamaniee@yahoo.co.uk)
  - H.I.G.S. Piyaruwan, Department of Soil Science, Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya 81100, Sri Lanka.
  - P.K.S.C. Jayasinghe, Department of Information and Communication Technology, Faculty of Technology, University of Ruhuna, Karagoda-Uyangoda, Kamburupitiya 81100, Sri Lanka.
  - P.A.N.R. Senevirathne, Department of Soil Science, Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya 81100, Sri Lanka.

J. Hydrol. Hydromech., Vol. 69, No. 4, 2021, p. 456 - 466, doi: 10.2478/johh-2021-0023
Scientific Paper, English

Katarina Zabret, Mojca Šraj: Relation of influencing variables and weather conditions on rainfall partitioning by birch and pine trees

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• General weather conditions may have a strong influence on the individual elements of the hydrological cycle, an important part of which is rainfall interception. The influence of general weather conditions on this process was analysed, evaluating separately the influence of various variables on throughfall, stemflow, and rainfall interception for a wet (2014), a dry (2015), and an average (2016) year. The analysed data were measured for the case of birch and pine trees at a study site in the city of Ljubljana, Slovenia. The relationship between the components of rainfall partitioning and the influential variables for the selected years was estimated using two statistical models, namely boosted regression trees and random forest. The results of both implemented models complemented each other well, as both indicated the rainfall amount and the number of raindrops as the most influential variables. During the wet year 2014 rainfall duration seems to play an important role, correlating with the previously observed influence of the variables during the wetter leafless period. Similarly, during the dry year 2015, rainfall intensity had a significant influence on rainfall partitioning by the birch tree, again corresponding to the influences observed during the drier leafed period.
  
  KEY WORDS: Throughfall; Stemflow; Rainfall interception; Rainfall microstructure; Boosted regression trees; Random forest.
  
  Address:
  - Katarina Zabret, University of Ljubljana, Faculty of Civil and Geodetic Engineering, Jamova 2, 1000 Ljubljana, Slovenia. Institute for Water of the Republic of Slovenia, Einspielerjeva 6, 1000 Ljubljana, Slovenia.
  - Mojca Šraj, University of Ljubljana, Faculty of Civil and Geodetic Engineering, Jamova 2, 1000 Ljubljana, Slovenia. (Corresponding author. Tel.:+386 1 4768 684 Fax.: Email: mojca.sraj@fgg.uni-lj.si)

J. Hydrol. Hydromech., Vol. 69, No. 4, 2021, p. 467 - 474, doi: 10.2478/johh-2021-0024
Scientific Paper, English

Eugene Balashov, Natalya Buchkina, Vladimir Šimanský, Ján Horák: Effects of slow and fast pyrolysis biochar on N2O emissions and water availability of two soils with high water-filled pore space

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• Biochars, depending on the types of feedstocks and technological conditions of pyrolysis, can vary significantly in their properties and, therefore, it is difficult to predict biochar-induced effects on nitrous oxide (N2O) emissions from various soils, their physical properties and water availability. The objectives of this study were (1) to quantify effects of slow pyrolysis biochar (BC) and fast pyrolysis biochar (PYRO) on physical and hydro-physical properties of sandy soil (Haplic Arenosol) and clayey loam soil (Gleyic Fluvisol), and (2) to assess corresponding N2O emissions from these two soils. The study included a 63-day long laboratory investigation. Two doses of BC or PYRO (15 t ha–1 and 30 t ha–1) were applied to the soils in combination or without nitrogen fertilizer (NH4NO3, 90 kg N ha–1). The obtained results have shown a significant decrease in the bulk density of sandy soil after it was amended with either rate of BC or PYRO. Water retention capacity of the soils in all the treatments with BC or PYRO increased considerably although no changes was found in the soil water-filled pore space (WFPS) which was higher than 60%. BC was increasing N2O emission rates from the sandy soil treated with N fertilizer, and reducing N2O emission rates from the clayey loam soil treated with N fertilizer. PYRO was more efficient and was reducing N2O emissions from both fertilized soils, but for the sandy soil the reduction was statistically significant only at higher dose (30 t ha–1) of the biochar.
  
  KEY WORDS: Biochar; Sandy soil; Clayey loam soil; Bulk density; Water retention capacity; N2O emission.
  
  Address:
  - Eugene Balashov, Department of Soil Physics, Physical Chemistry and Biophysics, Agrophysical Research Institute, Grazhdansky pr. 14, 195220 St. Petersburg, Russia. (Corresponding author. Tel.: Fax.: Email: eugene_balashov@mail.ru)
  - Natalya Buchkina, Department of Soil Physics, Physical Chemistry and Biophysics, Agrophysical Research Institute, Grazhdansky pr. 14, 195220 St. Petersburg, Russia.
  - Vladimir Šimanský, Department of Soil Science, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture, Tr. A. Hlinku 2, 94901 Nitra, Slovakia.
  - Ján Horák, Department of Biometeorology and Hydrology, Faculty of Horticulture and Landscape Engineering, Slovak University of Agriculture, Hospodárska 7, 94976 Nitra, Slovakia.